...Iran had nothing whatsoever to do with 9/11 — in fact, the Iranian regime was quite helpful to the United States when it went after Al Qaeda and its Taliban allies in Afghanistan.
Quick, alert the 9/11 Commisison - they will want to revise this part of their report:
Intelligence indicates the persistence of contacts between Iranian security officials and senior al Qaeda figures after Bin Ladin's return to Afghanistan. Khallad has said that Iran made a concerted effort to strengthen relations with al Qaeda after the October 2000 attack on the USS Cole, but was rebuffed because Bin Ladin did not want to alienate his supporters in Saudi Arabia. Khallad and other detainees have described the willingness of Iranian officials to facilitate the travel of al Qaeda members through Iran, on their way to and from Afghanistan. For example, Iranian border inspectors would be told not to place telltale stamps in the passports of these travelers. Such arrangements were particularly beneficial to Saudi members of al Qaeda.120
Our knowledge of the international travels of the al Qaeda operatives selected for the 9/11 operation remains fragmentary. But we now have evidence suggesting that 8 to 10 of the 14 Saudi "muscle" operatives traveled into or out of Iran between October 2000 and February 2001.121
...We have found no evidence that Iran or Hezbollah was aware of the planning for what later became the 9/11 attack. At the time of their travel through Iran, the al Qaeda operatives themselves were probably not aware of the specific details of their future operation.
After 9/11, Iran and Hezbollah wished to conceal any past evidence of cooperation with Sunni terrorists associated with al Qaeda.
The Iranian attempts to conceal their presumably unwitting involvement seem to have met with some success, at least on Planet Krugman.
UPDATE: Jon Henke is similarly struck by Krugman's claim of Iranian non-involvement.